Glucocorticoid may influence amyloid β metabolism in patients with depression

Epidemiological studies have demonstrated that depression may be a risk factor for Alzheimer's disease (AD); however, the biological mechanisms of the transition from depression to AD are still not clear. Changes of amyloid beta protein (A beta) metabolism and increased glucocorticoid (GC) levels have been found in both depression and AD. Moreover, several studies in animal models have demonstrated that GC administration changes A beta metabolism. To reveal whether GC affects amyloid metabolism in patients with depression, we evaluated serum levels of A beta 40, A beta 42 and cortisol at admission in 187 inpatients with major depressive disorder (MDD) and 224 healthy comparisons. Additionally, we re-evaluated the serum levels of A beta s in 27 patients with MDD 1 year later. The results of multiple regression analyses revealed that serum cortisol and A beta levels are not correlated at the time of admission. However, serum cortisol levels at admission correlated with serum A beta 42 levels and A beta 40/A beta 42 ratio 1 year later. These findings suggest that increased cortisol in patients with MDD may influence the metabolism of A beta over prolonged periods of time.